In the hills of Palestine, next to a village called Anin, three groups of people stood this Monday afternoon amid clouds of tear-gas and the boom of bullets to yell at each other. I was standing on one side of Israel's new "security fence" with the largest group, a band of 100 Palestinian villagers and 80 members of the International Solidarity Movement (ISM), the organisation that brings committed internationalists from across the world to support non-violent Palestinian resistance. On the other side were Israeli protesters, disgusted by their own government's inhumanity; and in between us stood a group of teenage soldiers fighting an old man's war they barely seemed to understand.

In the hills of Palestine, next to a village called Anin, three groups of people stood this Monday afternoon amid clouds of tear-gas and the boom of bullets to yell at each other. I was standing on one side of Israel's new "security fence" with the largest group, a band of 100 Palestinian villagers and 80 members of the International Solidarity Movement (ISM), the organisation that brings committed internationalists from across the world to support non-violent Palestinian resistance. On the other side were Israeli protesters, disgusted by their own government's inhumanity; and in between us stood a group of teenage soldiers fighting an old man's war they barely seemed to understand.

Their job was to guard the wall that is being built deep into the West Bank, splitting Palestinian land in two, dividing farmers from their fields, chopping families in half. Even the ultra-pro-Israeli George Bush, as he shared canapés with Ariel Sharon in Washington DC over the last few days, has condemned the building programme as a terrible mistake.

The ISM and Palestinians came on Monday to symbolically destroy a patch of this immoral barrier. Two ISM negotiators began the protest by telling the troops what they were here to do - and with that, the destruction of one patch of this steel construct, which is three times the height of the Berlin Wall, began. Within seconds, five people had been shot with rubber bullets, including two of my friends; and then there was a descent into an angry, chaotic mess.

One person glided through the spluttering and bleeding that followed with an infectious sense of total calm. Her name is Huwaida Arraf, a 27 year-old Palestinian-America who, with her Jewish husband Adam Shapiro, founded the ISM two-and half-years ago. As I saw her talk calmly and firmly to an Israeli soldier, asking for an explanation, I thought of the Vietnam film Apocalypse Now. There is a character in the movie called "Wild Bill" who is described as "one of those guys that had that weird light around him. You just knew he wasn't gonna get so much as a scratch out here."

Huwaida has that weird light. Most Palestinians resist the Occupation in their minds but not with their flesh: they still flinch when an Israeli gun is turned on them, they still retreat when a soldier howls that they should. Huwaida walks towards gunfire with an air of tranquil certainty that she belongs here and the soldiers, with their fences and guns and tanks, do not.

Over coffee the day before the protest, she explained to me how she does it. "I am stronger than some soldier turning his tank barrel at me. When I stand in front of him, unarmed and in peace as I walk around my own city, I know that he is the weak one. Non-violence is much more threatening to the occupation because it shows we are morally strong." She continues, "You know, at a demonstration against the closure of the Bir Zeit University on the West Bank, we marched in protest, and they opened machine gun fire on us. We stayed standing. When the dust cleared, we carried on marching forward with the students who just wanted to go to school. We chose not be frightened of an occupier who chooses massive and disproportionate violence."

The ISM is to our day what the International Brigade was to the Spanish Civil War. Left-wingers from countless countries have gathered here with nothing to unite them but their hatred of oppression; the ghost of George Orwell is no doubt smiling on them. The ISM's actions are mostly solid and practical: for example, they march Palestinian children to school during Israeli-imposed curfews because, as one ISMer explained, "Nobody can justify sealing children in their homes for months on end and denying them an education. Nobody." Sometimes, they reach for the symbolic: last week, they painted the words "Return To Sender" on an Israeli tank.

Already, the movement has generated myths and folk-heroes. I visited Rafah last week, the Gaza Strip town where an Israeli bulldozer killed 26 year-old American Rachel Corrie as she tried to protect the house of an innocent Palestinian doctor. The town looks like it has been hit by a vast bomb. Rubble and the possessions of newly-homeless families are strewn like rubbish across the streets. The patch of dirt and earth where Rachel died is now a site of near-pilgrimage, and hers was only the first of three ISM deaths so far this year. Yet despite all this danger, there are now nearly 200 ISMers in Palestine who could just as easily be lolling on a beach in Ibiza, and more are expected throughout August.

Predictably, the Israel defence establishment has tried to bulldoze the ISM's reputation. They have claimed that the group are not "in favour of human rights, as they claim" but "pro-Palestinian" - a fatuous distinction. They have even tried to link the ISM to Palestinian terrorism with a series of silly charges that crumble on the slightest analysis. A claim circulated by the Associated Press (and reported gleefully in US right-wing circles) that Kalashnikovs had been found in an ISM office was completely retracted by AP and even the Israeli army itself when it emerged that it was totally false. Two British suicide bombers did, it is true, meet some ISM representatives in Gaza earlier this year, as anybody can; but nobody has suggested that the ISM knew their purposes, or that they offered them more than a cup of tea. That is the sum of the Israeli government's rather pathetic charges against the ISM.

Before I joined the group in Anin, I braced myself for the possibility that many of the ISM's members, understandably disgusted by the occupation, would question Israel's right to exist alongside a Palestinian state at all --a political stance I am very uncomfortable with. My fears were totally unfounded. A few ISMers I met believed in a binational solution - one big state of both Israel and Palestine - but most of the people I spoke to argued strongly for a two-state solution.

There are people who want to destroy Israel and push the Jews into the sea, and we must never underestimate the danger they pose; but the ISM is definitely not on their side. When one lone protester in Anin tried to chant, "Bush, Sharon, you should know/ We are all the PLO," he was universally shot contemptuous looks and told to shut up. If this conflict were the other way round and the Palestinians were oppressing the Israelis and denying their right to national self-determination, I have no doubt that most of the current ISMers would come to protect the Jews. If only the Jewish people had had such friends for the last two millennia, there would be an awful lot more of them alive today.

As the shouting died down and the sting of tear-gas died away, a Palestinian man named Mohammed Aktar turned to me and shook my hand so hard I feared it would snap. "Thank you for coming," he cried. "We used to think that nobody cared and we were alone in this fight. We thought the world had forgotten us. Now we know that there are people everywhere who think we matter, who know we are human beings and not animals. Now we know that this occupation must one day end."